Laminating resins having low organic emissions

ABSTRACT

A laminating resin comprising (A) an acrylated or methacrylated cycloaliphatic epoxide, (B) an acrylated or methacrylated alkoxylated bisphenol-A, in a weight ratio of (A) to (B) of about 3 to 1 to about 1 to 5, and (C) about 5% to about 50%, based on the total composition, cyclohexyl methacrylate. Vinyl toluene and ethylene glycol dimethacrylate are also used to modify certain properties of the resin.

TECHNICAL FIELD

This invention relates to resin compositions which cure as they areshaped, laminated, brushed, sprayed or otherwise placed into the spacewhere they are to form a product; such resins are broadly known aslaminating reins, commonly have an unsaturated polyester resin base, andnearly always are employed in a solution of an organic monomer such asstyerene. The organic monomer is intended to copolymerize with the resinbut typically and notoriously may also tend to volatilize in significantamounts into the workplace environmental the present invention employs avinyl ester resin rather than a conventional unsaturated polyester, incombination with a particular crosslinking agent. It can be used inexisting equipment, procedures, and workplaces, but emits far lessmonomer than the typical laminating resin heretofore.

BACKGROUND OF THE INVENTION

Many attempts have been made to devise laminating resins having lowvolatile emissions and still meet the physical specifications and otherdesirable properties of the end products, while remaining relativelyeasy to use. In Lee U.S. Pat. No. 4,465,806, for example, a more or lessconventional unsaturated polyesters resin is combined with, instead ofthe usual styrene, a reaction product of a polyepoxy compound andacrylic or methacrylic acid which may be the diacrylate of apolyglycidyl ether of bisphenol-A.

Cycloaliphatic epoxides are well known. They have been reacted withvarious other materials and used in various environments. See thebulletin on cycloaliphatic epoxide systems published by union CarbideCorporation. The reaction product of such materials with acrylic acid ormethacrylic acid are not well known, and although aliphatic epoxys areenumerated as potential ingredients in some vinyl ester resin patents,they are not demonstrated in any nor are they mentioned as a possibleuse for cycloaliphatic epoxy resins in any of Union Carbide's (themanufacturer) literature. Further, when we formed these vinyl esterreins we found it necessary to depart radically from the accepted ratioof one monounsatured acid per unreacted epoxy group to a preferred ratioof one monounsaturated acid per 1.6 epoxy groups. This indicted adifference chemistry from that found in forming BPA epoxy vinyl esterresins.

Ethoxylated dysfunctional, bisphenol-A has been used in the past as aningredient in various types of resins, generally resins which include asignificant diisocyanate component, as in Ford, Jr. et al U.S. Pat. No.3,876,726.

However, we are not aware of ny combinations in the prior art of thetypes of laminating resins we employ in our invention, namelycombinations of alkoxylated difunctional bisphenol-A and vinyl esterresins based on cycloaliphatic epoxides.

SUMMARY OF THE INVENTION

Our new laminating resin comprises three major components.

The first component is an acrylated or methacrylated cycloaliphaticepoxide. That is, it is a composition made by reacting a compoundcontaining a cycloaliphatic epoxide group of the formula ##STR1## withan organic acid of the formula ##STR2## where R is hydrogen or methyl toform a compound containing a group of the formula ##STR3##

The remainder of the compound may be any one of vinyl, oxide, methylcarboxylate, and adipate but should not be nay configuration thatresults in a viscosity higher than 1,000 cps.

The second component is a diacrylate or dimethacrylate of alkoxylatedbisphenol-A of the formula ##STR4## where m and n are independentlynumbers from 1 to about 10, R is H or CH₃, and each group subtended by pand q is independently selected from 2, 3, and 4. These two ingredientsmay be present in weight ratios of about 3:1 to about 1:5, preferablyabout 2:1 to about 0.7:1.

The third component is cyclohexyl methacrylate. It may be present inamounts (based on the total of the first two ingredients) between about20% and about 70%, although we prefer to use about 30% to about 50%.

The composition may also include up to about 30% based on the total ofthe major ingredients of an additional dimethyacrylate crosslinkingmaterial such as ethylene glycol dimethacrylate, and up to about 20%vinyl toluene for viscosity adjustment and or its contribution as amonomer. Since out objective is to using a composition which works verywell as a laminating resin without significant styrene emissions, theaddition of styrene to the recipe defeats that purpose and is notrecommended, but the composition will continue to be operable as anexcellent laminating resin even though some styrene--say, up to about10%, is included. The composition will also tolerate many other maineingredients known to be useful in the unsaturated polyester andlaminating art.

DETAILED DESCRIPTION OF THE INVENTION

While the problem at hand is to create a formulation which drasticallydiffers from commercial standard laminating resins in terms of volatileemissions during application, the market dictates that it must beaccomplished without significantly altering the widely used equipmentand techniques of application. Accordingly, the following criteria areto be kept in mind at all times:

1. educed emission of volatile organic compounds--regulations willbecome more stringent with time.

2. Less potential hazard to human health and theenvironment--regulations will also become more stringent with time.

3. Minimal increase in cost when commercialized, and reason to believecost will be reduced in the long run.

4. Compatibility between components of the resin system.

5. Reactivity that is similar to that of styrenated polyester resins.

6. Viscosity that is similar to that of styrenated polyester resins--100to 300 cps.

7. physical properties similar to or better than those of styrenatedpolyester resin.

8. Ability to wet glass and bound to other components of an assemble.

Persons skilled in the at will realize that number 7, relating tophysical poverties of the final product, can be itself include severalimportant specifications. Thus, the problem is not simply one of findinga monomer which is not as volatile or objectionable as styrene. Rather,many criteria have to be balanced, and, with thousands of chemicals toconsider, analysis of the combinations and their effects is extremelydifficult. One must decide on the important functions and properties,settle on a systematic but simple screening process, and try to developa short list of prospective formulations which have a good chance ofmeeting all the criteria within a practical time period.

Examples of cycloaliphatic epoxides which may be reacted with acrylicacid or methacrylic acid to form the acrylated cycloaliphatic epoxideswe use in our invention are:

3,4-epoxy cyclohexylmethyl-3,4-epoxy cyclohexane carboxylate ##STR5##vinyl cyclohexene dioxide ##STR6## Bis(3,4-epoxy cyclohexyl) adipate##STR7## and 1,2-epoxy-p-vinylcyclohexene ##STR8##

Preparation of a typical methacrylate cycloaliphatic epoxide useful inour invention is as follows:

1.5 mole of 3,4-epoxy cyclohexyl-methyl-3,4-epoxy cyclohexanecarboxylate was charged into a reactor, heated to 190° F. and a smallamount of tetramethyl ammonium chloride was added; then an inhibitedmethacrylic acid (1.875 moles) was added dropwise over a period of twohours. The mixture was then elevated to 225° F. and kept at 225° F. orhigher until the reaction was complete as indicated by a viscosity ofGardner A to D on a 50/50 mixture with inhibited styrene and an acidnumber below 15. The resin was then cooled. This resin was designatedVE4221.

We have found that molar ratios of unsaturated to cycloaliphatic epoxidehigher than about 1.30 will create a reaction mixture that is tooviscous when the acid number comes into range; on the other hand, theratio should not be less than 1.00 because the resultant resin will nothave the desired properties.

Liquid resin properties measured in the experiments reported below weregel time, (reported in the tables herein in minutes and seconds, as13:17, for examples), room temperature interval time, which is thehighest temperature reached in a 100 g mass of resin during the curingprocess, Brookfield viscosity, and Barcol hardness by ASTM D2583. Forvolatile emissions, we followed the Rule 1162 Standard Method for StaticVolatile Emissions of the south Coast Air quality Management District(California). The clear castings tests adopted were as follows:

1. Tensile strength - ASTM D638.

2. Tensile modulus - ASTM D638.

3. Elongation - ASTM D638.

4. Flexural strength - ASTM D790.

5. Flexural modulus - ASTM D790.

6. Heat deflection temperature - ASTM D648.

7. Water absorption at 150° F. - ASTM D570 (modified).

The water absorption test was modified as follows: the temperature wasset as 150° F. and long term immersion was set as one week. In the datareported in Table I, MR 14059 is: a vinyl ester resin composed of 2.0moles Epon 828 epoxy resin (a product of Shell Chemical Corp.), 1.0moles bisphenol-a and 2.0 moles methacrylic acid. Ssartomer CD480 isethoxylated bisphenol-a dimethacrylate where m and n in the aboveformula, total 10. Sartomer 348 is ethoxylated bisphenol-Adimethacrylate where m and n in the above formula are both 1. Mod L is25% hydroquinone and 75% propylene glycol.

From the data in Table I, it can be seen that formulation N, acomposition of this invention, has better than acceptable resinproperties and clear casting properties, and has volatile emissions farless than any of the others which are based on a vinyl ester resin notof this invention.

                  TABLE I                                                         ______________________________________                                        RESIN        E       T       U     V     N                                    ______________________________________                                        MR 14059     60.00   30.00   35.00 30.00 --                                   VE4221       --      --      --    --    30.00                                Sartomer CD480                                                                             --      20.00   15.00 10.00 30.00                                Sartomer 348 --      20.00   20.00 25.00 --                                   EG Dimethacrylate                                                                          20.00   20.00   20.00 25.00 --                                   Vinyl toluene                                                                              20.00   10.00   10.00 10.00 --                                   Cyclohexyl Meth-                                                                           --      --      --    --    40.00                                acrylate                                                                      Mod L        0.10    0.15    0.20  0.15  0.10                                 RESIN PROP-                                                                   ERTIES                                                                        Gel time, min:sec                                                                          4:29    10:56   11:38 12:18 22:45                                Interval, min:sec                                                                          2:36    2:52    3:38  3:22  6:30                                 Exotherm peak, °F.                                                                  309     285     284   302   262                                  Viscosity, cps, 75° F.                                                              6,780   396     990   538   166                                  1162 Emissions, G/M2                                                                       16.4    12.1    13.9  9.7   3.6                                  Barcol hardness                                                               45 minutes   52      48      49    53    43                                   One hour     52      49      51    52    43                                   24 hours     53      48      51    56    43                                   CLEAR CASTING                                                                 PROPERTIES                                                                    Tensile strength, psi                                                                      7,476   9,218   8,963 8,232 10,819                               Ten. modulus, 10-5 psi                                                                     0.494   0.379   0.440 0.470 0.467                                Elongation, %                                                                              1.8     4.3     2.5   2.0   3.4                                  Flexural strength, psi                                                                     19,198  13,662  16,004                                                                              15,647                                                                              15,547                               Flex modulus, 10-5 psi                                                                     0.512   0.360   0.466 0.508 0.463                                Heat deflect. temp, °F.                                                             204     167     195   217   186                                  Water absorption, %                                                           at 150° F.                                                             One day      0.52    0.69    0.89  0.77  1.15                                 7 days       1.17    1.21    1.21  1.02  1.93                                 ______________________________________                                    

We claim:
 1. A laminating resin composition comprising (A) an acrylatedor methacrylated cycloaliphatic epoxide, (B) an acrylated ormethacrylated alkoxylated bisphenol-a, in a weight ratio of (A) to (B)of about 3 to 1 to abut 1:5, and (C) about 5% to about 50%, based on thetotal composition, cyclohexyl methacrylate.
 2. Resin composition ofclaim 1 wherein the ratio of (A) to (B) is about 2:1 to about 0.7:1. 3.Resin composition of claim 1 wherein component (C) is about 10% to about30% of the total of (A), (B), and (C).
 4. Composition of claim 1 whereinthe acrylated cycloaliphatic epoxide has the formula ##STR9## where eachR is independently hydrogen or methyl.
 5. Composition of claim 1 whereinthe acrylated alkoxylated bisphenol-A has the formula ##STR10## where mand n are independently numbers from 1 to 10 and each group subtended byp and q is independently selected from 2, 3, and 4.